WHOA Tomos owners read this! Warped head?

QuickReference /

Apr 02, 2008 01:45AM

Today I was finishing up my Airsal A35 build. I put the newly kitted motor in the bike, turn it over a few times and it wont start. I keep trying and I notice there is gas and air shooting out from between the cylinder and the head. I inspected the head for damage before I put it on, seemed right. So I tighen down the bolts more, try it again, same thing. I tighten the bolts more, same thing. I tighten the bolts more and "CLING" one of the studs is broken. SHIIIIT. I look over and see a spare A35 motor sittin on the bench, run over to it and start taking the top end apart. Took the head off, had to pound the cylinder off with a hammer (rusted to shit) but got it off too. Pull the best looking stud off, go back to the main engine. Take the head off of it and smile. The stud broke above the cylinder so I can replace it without taking the pipe, cylinder and carb off. I get the new stud in and think hmm, maybe I should try the other head. Put that one on, tighen it down turn the bike over VRUUUMMMMM starts right up. I look at the first head I had, and nothing looks obviously wrong. My guess is that it somehow got warped or something like that. The whole head without gasket is new to me... I was blessed (or genious u decide) to have a spare motor, but I can see this happening to another person so Im writing this here hoping it may help.

Re: WHOA Tomos owners read this! Warped head?

TaylorN. /

taylor

Apr 02, 2008 02:51AM

Heads warp alot. When metal heats up, it expands, so if the inner portion of the head gets really hot, and the outer part stays cool then it warps out. If its not warped to bad, then either use a cinder block or a big flat piece of steel or marble or whatever and lay a pice of sand paper, like 220 or maybe a little courser (don't need sand paper with cinder block) and squirt some oil on the paper and start making figure 8s with the head. it will surface the head and make it perfectly (or close enough) flat.

Re: WHOA Tomos owners read this! Warped head?

QuickReference /

quickreference OP

Apr 02, 2008 03:36AM

Yeah, I just never seen one not seal when it was this close to perfect looking. I even put it on a piece of glass and looked under it to see if there is light comming through and didnt see any. I used the other head and it worked fine, I think Ill scrap this one for all the trouble it caused me!

Re: WHOA Tomos owners read this! Warped head?

scott /

sweed88

Apr 02, 2008 03:01PM

hope u used a fresh head gasket. seems like u squeezed the crap out of the other one. use a torque wrench and torque it to spec. that way u know u did it right and the head will sit more true because of equal pressure all around the head.

Re: WHOA Tomos owners read this! Warped head?

QuickReference /

quickreference OP

Apr 02, 2008 03:21PM

Thats the thing! Tomos dont use a head gasket for whatever reason. Its metal to metal, and I guess if the metal is a tiny fraction of a millimiter off no go. Now normally the gasket would take care of it, but I guess thats too hard of a concept in slovenia lol

Re: WHOA Tomos owners read this! Warped head?

scott /

sweed88

Apr 02, 2008 03:29PM

the a35 does use a head gasket. the a3 doesn't. are u sure u have an a35? mopedjunkyard has the head gaskets for 6 bucks. maybe that was ur problem all along?

Re: WHOA Tomos owners read this! Warped head?

Saabsonettguy . /

saabsonettguy

Apr 02, 2008 04:04PM

Most A35's came without a gasket. Its not needed if the mating surfaces are clean and flat.

Re: WHOA Tomos owners read this! Warped head?

jack /

glhman222

Apr 02, 2008 04:30PM

if you tighten them too much (as to beak a stud) you probably warped the head by your own fault even worse

Re: WHOA Tomos owners read this! Warped head?

scott /

sweed88

Apr 03, 2008 05:43PM

all of mine have had a gasket. i tihnk alot of people take them out trying to raise compression.

Re: WHOA Tomos owners read this! Warped head?

Adam /

1adam1

Apr 04, 2008 10:28PM

Have the warped head decked, you will get higher compression, and better low end.

Re: WHOA Tomos owners read this! Warped head?

mike /

assa9

Apr 09, 2008 01:46AM

my 2003 targa did not have a head gasket when purchased brand new.

Re: WHOA Tomos owners read this! Warped head?

Brendan Chenelle /

toehead2

Apr 09, 2008 06:33PM

Maybe it is not warped, and that stud was necking and not allowing it to hold it to the torque spec on that side.

Re: WHOA Tomos owners read this! Warped head?

Crazy Hakachukai /

crazy_hakachukai

Apr 10, 2008 03:32AM

A35's do not have a head gasket. It's metal on metal.

I don't know if you warped your head or not. But I can tell you this:

When you put a stock head on an Airsal cylinder, if you look at it carefully you will see that almost ALL of the mating surface of the head is not even used.

This happens because the bore of the Airsal cylinder is much larger. So it just barely even touches the edge of the heads mating surface. The amount of mating material that makes contact is actually so small that it's kind of scary (but I've never had any problems with it).

I'm willing to bet that you simply had a small nick, or some imperfection that was way out near the edge of the head. So when you put it on an Airsal it won't seal.

I bet if you put that head back on a stock A35 it will still run perfectly. (unless it's not been damaged by the above incident).

Re: WHOA Tomos owners read this! Warped head?

QuickReference /

quickreference OP

Apr 10, 2008 04:21AM

The previous owner may have done something to it while trying to fix the ped. When I got it, it was already not running and had bad compression. It was allowed to sit without a plug for a long time in the guys garage, so I attributed low comp to rusted piston rings. Now that I think of it, the head is more likely to have been it. The stock cylinder and piston/piston rings I removed seem fine. Anyways, long story short the spare head works great. This thing takes off like crazy. Ill be selling this Tomos and a very nicely tuned up Moby soon =)

MOPED ARMY

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